Neurodevelopment and the Dynamic Brain Flashcards Preview

Neuroscience > Neurodevelopment and the Dynamic Brain > Flashcards

Flashcards in Neurodevelopment and the Dynamic Brain Deck (27)
Loading flashcards...
1
Q

Neural Stem Cells

A

Multipotential cell, lining the neural tube, extensive capacity for self-renewal.

In adults, neural stem cells line the ventricles forming the sub ventricular zone.

They give rise to PROGENITOR CELLS.

2
Q

Progenitor Cells

A

Progenitor cells can also divide, however they eventually produce non-dividing cells:

Neuroblasts and Glioblasts.

Sam Weiss discovered that stem cells remain capable of producing neurons and glia throughout adulthood and even in aging brain.

Therefore, neurons that die in an adult brain should be replaceable.

Prolactin, Gene Transcription, Epigenetics are involved in ensuring stem cells become mature neurons/glia.

3
Q

Neuroblasts (Non-Dividing Progenitor Cells)

A

Develop into mature neurons.

4
Q

Glioblasts (Non-Dividing Progenitor Cells)

A

Develop into mature glia.

5
Q

Prolactin (Maturity of Neurons/Glia)

A

Naturally occurring hormone that helps replace lost neurons in animal models.

6
Q

Gene Transcription (Maturity of Neurons/Glia)

A

Turning on the correct genes that dictates a stem cell will become a neuron and not a skin cell.

7
Q

Epigenetics (Maturity of Neurons/Glia)

A

Different cells have different gene expression, leading synthesis of different proteins and ultimately different phenotypes.

DNA methylation: a methyl group is attached to the DNA to turn off gene transcription. It alters gene expression dramatically during development. Different methylation patterns are needed to trigger the differentiation of STEM cells.

Methylation patterns are influenced by neighboring cells, chemicals, stress, etc.

8
Q

Neurotrophic Factors

A

Chemical compounds that act to support growth and differentiation of neurons.

Keeps adult neurons alive and healthy.

Epidermal Growth Factor stimulates stem cells to produce Progenitor Cells.

Basic Fibroblast Growth Factor stimulates progenitor cells to produce Neuroblasts.

Neuroblasts serve as an all-purpose neuron until they are exposed to certain growth factors in other areas.

These chemical messengers will dictate the ultimate fate of the neuron.

9
Q

What are the neurodevelopmental stages?

A

Cell Birth, Cell Migration, Cell Differentiation, Cell Maturation, Synaptogenesis, Cell Death, Myelogenesis.

10
Q

Cell Birth (Neurogenesis, Gliogenesis)

A

Neurogenesis is largely complete by 5 months, and during this time, the brain is resilient to injuries and/or trauma.

11
Q

Cell Migration

A

Begins just after neurogenesis is complete; lasts for 6 weeks.

12
Q

Cell Differentiation

A

Begins after migration is complete; more or less complete at time of birth.

13
Q

Cell Maturation (Dendritic Development, Axonal Growth)

A

This process occurs for years, well into adulthood; growth of dendrites and axons.

14
Q

Synaptogenesis (Formation of Synapses)

A

Each neuron begins forming its own networks.

Can synapse with hundreds or thousands of other neurons.

15
Q

Cell Death

A

If you don’t use it, you lose it.

16
Q

Myelogenesis (Formation of Myelin)

A

Neuronal Networks become more efficient in their communication.

Sign of neurodevelopmental maturity.

Occurs well into adulthood.

17
Q

Subventricular Zone

A

Contains a primitive map of the Cerebral Cortex.

Cells formed in certain regions of the SVZ migrate to certain cortical locations.

18
Q

Radial Glial Cells

A

Form a path that extends from the SVZ to the surface of the cortex.

Undifferentiated progenitor cells follow this path.

19
Q

How do cells get to their final destination?

A

Cortical layers form from inside out.

Most inner layers are first to form.

Intracellular signals progressively restrict the choice of traits a cell can express.

Therefore, the emergence of a cell type is a combination of genetic instructions, timing and signals from neighboring cells in the local environment.

20
Q

What does a maturing neuron need?

A

Dendrites, Axon, Growth Cones, and Filopod.

21
Q

Dendrites

A

Provide surface area for synapse formation.

Branching of dendrites.

Growth of dendritic spines.

22
Q

Axon

A

Extending to appropriate target to initiate synapse formation.

Occurs very rapidly.

Various molecules attract or repel axon tip, thus guiding it through a very complex terrain.

23
Q

Growth Cones

A

These are growing axons.

They are a response to:
Cell-Adhesion Molecules - Secreted from cell or lie on cell surface.

Tropic Molecules - Secreted from target cells and carry a “come here” or “go away” message. Netrin is the only known group.

24
Q

Filopod

A

Growth cones extend shoots called filopod.

When filoppod reaches an appropriate target, the others follow.

25
Q

Synaptic Pruning

A

The brain uses apoptosis as a method of pruning.

Genetic signals, experience, hormones, stress, etc. are all factors that can initiate apoptosis.

~42% of all synapses in human cortex are lost.

Neurons become dependent on their target cell and will die without them.

Nerve Growth Factor is a neurotrophic factor produced by cells that regulate neuronal survival.

Neurons that are deprived of NGF will undergo apoptosis.

Cortex continues to thin from ages 5 to20.

26
Q

What is Neural Darwinism?

A

Competition drives neuronal loss.

Environmental pressure leads to competition amongst neurons.

27
Q

Myelination

A

Frontal Lobe is the last brain region to mature (pruning occurs into the 20’s).

This process can be used as an index of neuronal activity.

Early-Myelinating areas control simple movement, while late-myelinating areas control neuronal maturity.